The present invention relates generally to corrugated elliptical waveguides or horns, and specifically to the determination of the depth of corrugation grooves of the waveguides or horns.
No definite design methods have hitherto been available to determine the depth of corrugation grooves of a corrugated elliptical waveguide or horn to excite a balanced hybrid mode, and the depth determination was based generally on the concept that a balanced hybrid mode exists when the corrugation grooves have a depth in the range between 1/4 to 1/2 of a wavelength in the free space. One disadvantage of this prior method is that the balanced hybrid mode is not perfect and this imperfection caused even the most perfectly adjusted waveguide or horn to generate cross polarizations by as much as -30 dB with respect to the main polarization. As a result, the prior art waveguide or horn when mounted on a broadcasting satellite as the primary radiator of a reflector antenna has experienced difficulties in meeting the cross polarization limits set by the World Administrative Radio Conference on Broadcasting Satellites 1979 (known as WARC-BS '79). The depth determination by experiments will involve solving an infinite number of possible combinations of odd modes (excitations on the major axis of ellipse) and even modes (excitations on the minor axis of the ellipse).